CyanogenMod is an open-source firmware distribution for most Android smartphones and tablets available on the market. It's being developed by Android Open Source Project with the help of useful contributions also made within the Android community. CyanogenMod aims to provide Android users with invaluable opportunities to enhance security, privacy, and customization options of their devices. With Cyanogenmod, for instance, you can escape the Google's "radar" (by simply not installing its applications), encrypt your sensitive data, remove all the bloatware supplied by the vendor of your device, and enable or disable the root access with just one click. Also, you get frequent security updates and the latest version of the Android operating system, even if your vendor no longer supports the device. On some smartphones and tablets it's even possible to overclock the CPU and give them extra boost. The simplest way to install CyanogenMod is to use the installer. But, unfortunately, at the moment it's not available anywhere on the CyanogenMod websites due to security issues.
To check whether your device can get such a firmware distribution, visit the CyanogenMod web page of officially-supported devices.
Once you find your smartphone or tablet there, click on the «how to install» page and receive complete installation instructions. If you can't find a specific device on this list or a CyanogenMod build hasn't been updated for a long time, you can always study the XDA forum, where programmers may have already added support for your device or made some necessary customizations.
Remember (!) that installing a custom ROM or rooting your device may void the warranty.
Before we continue, here's some terminology that is used in the world of custom ROMs:
Bootloader is a special subroutine available on most devices, which enables a manufacturer to flash a device with new firmware.
Recovery is a limited boot mode, independent of your normal Android operating system. Basically, it's a special mode which lets you make a complete backup of your operating system and data, restore a previous backup, install a new ROM, clear caches, remove user-specific data, etc.
The only difference in the installation process between various devices is the way of delivering recovery to the smartphone or tablet. The CyanogenMod wiki is well written and you just need to carefully follow the step-by-step instructions. In most cases the installation implies getting root access to the device and/or to the bootloader (which is as simple as powering your device with a specific key combination pressed) and loading a recovery image file with specified software.
Once you got Recovery running on your device, you are able to install any available CyanogenMod build. Find the Cyanogenmod build for your device (it is supplied as a .zip file, but do not unpack it) and download it to the SD-card or internal memory of your device. Enter the Recovery mode. Always remember to back up before installing custom ROMs so choose the «Backup» option in the recovery mode and wait for it to complete. Select «Wipe/Factory reset» to clean your current ROM. Then choose the «Install» or «Install .zip file» option, find the CyanogenMod .zip file that you've downloaded and start the installation process. Congratulations, you have your CyanogenMod installed! CyanogenMod does not come with preinstalled Google apps (you won't get Google services, Gmail, or even the Play market). If you wish to install those, you just need to get another .zip file and launch it the same way from the Recovery mode.
That's it! And remember to install Droid Informer once you are done!